Osteoarthritis (OA) is the leading cause of activity limitation in older women. Yet, there is little data about risk factors for and consequences of the disease in older women. Osteoporosis is also very common, and studies suggest there is an inverse association between the risk of osteoarthritis and the risk of osteoporosis. Whether increased bone density is a pathogenic factor in the development of OA is uncertain. This question is particularly important if interventions to reduce the risk of osteoporosis also increase the risk of OA. The best study would measure bone mass near joints that are affected by OA. Risk factors for OA of different joints are different, suggesting that the pathogenesis of OA may vary by site. Bone mass also varies by anatomic site within individuals. Therefore, we will study bone mass in the hip in relation to hip OA, bone mass in the radius in relation to hand OA, and bone mass in the spine in relation to spine OA. We will also examine other risk factors specific to hand, hip, and spine OA, and compare risk factors for different joints. This study takes advantage of the "Study of Osteoporotic Fractures" (SOF), a cohort of 9712 women age 65 and over who already have X rays of the hip, hand, and spine, bone mass measurements of the radius, os calcis, femur, and lumbar spine, and measurements of many risk factors and outcomes relevant to OA. New data for this study will be collected as part of the second SOF examination, in progress until late 1990. Data that have already been collected for SOF, plus new data collected for this study will allow us to 1) test the hypothesis that there is an inverse association between OA and osteoporosis; 2) test the hypothesis that risk factors associated with a decreased risk of osteoporosis are associated with an increased risk of OA; 3) describe the associations among hip OA, hand OA, and disc degeneration in older women, and to describe and compare selected risk factors for subsets of OA defined by anatomic site and pattern of joint involvement; and 4) describe the pain and functional disability experienced by older women with radiographic OA of the hips, hand, and spine. We will read the hip X rays of all 9712 SOF participants for hip OA, and the X rays of 1500 participants for hand and spine OA. The large SOF population will yield more than 260 cases of hip OA. Radiographic assessments of OA will include standard 0-4 gradings, as well as quantitative measures of the severity of specific abnormalities. This proposal requests funds to read the X rays, to collect a small amount of new data on risk factors and outcomes of OA, and to analyze the data. Thus, the objectives of this study can be achieved efficiently without organizing a new study. This study will also lay the ground work for longitudinal studies about the progression and outcome of OA; the SOF cohort will continue to be followed, and future clinic visits including repeat radiographs and bone density measurements are planned.